Manufacture of heat-exchange apparatus



Jan 6, 1931. P. c. KALLocH. JR

MANUFACTURE OF HEAT EXCHANGE APPARATUS Filed Dec. 15, 1928 f, ag

A TTORNEYS.

' INVENTOR. @ne/1 /f/a//oc/f l f v? Patented Jan. 6, 1931 PATENT OFFICE PARKER C. KALLOCH, JR., OF GREAT NECK, NEW YORK MANUFACTURE OF HEAT-EXCHANGE APPARATUS Application mea December 15, 1928. serial No.' 326,343.

My invention relates to manufacture of heat exchange apparatus for heating or cooling a medium surrounding the apparatus, or for heating or cooling a medium contained within or passed through the apparatus, as for example radiators for the heating of buildings, the cooling of automobile motors, etc.

Specifically the invention provides for a method of attachment of members-having extended surfaces, such as fins or flanges, to the tube or body of the heat exchange apparatus, for increasing the efficiency of the unit.

Various methods have been employed to provide such a tube With extended surfaces.

One such method consists in casting extensions, ribs or fins integral with the tube. This method is very expensive, and furthermore can be used only with certain alloys having the properties which enable them to be readily cast.

Another method consists in forming sheet metal ns with perforations slightly greater than the external diameter of the tube, spacing such fins along the tube and securing them thereto by soldering, welding, brazing or dipping. This method is objectionable in that the joint is likely to wear or work loose by reason of unequal expansion and contraction of fin and tube. Frequently gaps are left between the fin and tube so that a poor contact is obtained which results in poor transmission of heat. v

According to a third method fins perforated as above mentioned are formed of comparatively thick sheet metal and after being spaced upon the tube the latter is expanded by a mandrel so as to canse the fins to become embedded within the material of the tube.

Since copper has a high coefficient of heat conductivity, it is a desirable material to use, but on the other hand there is a tendency for the tin to buckle or Warp and in order that such tendency may be successfully resisted the copper sheet must be of at least .026f thickness. The use of thinner sheets is objectionable not only on account of buckling, but also because it cuts down the eliciency of the heat transmission.

In accordance with the present invention the fins are formed of thin resilient sheet metal, for example copper, in which an opening is punched and the material surrounding such opening drawn to form a flange. The opening is substantially smaller in diameter than the external diameter of the tube, and the ltube is forced into such opening, thereby flexing the flange or the part by Which it is united to the body of the lin. The shape of the flange is such that when the flange or its uniting part is flexed the flange extends longitudinally along the surface of the tube for a substantial distance. Furthermore, by reason of the resilient character of the material the' flange presses tightly against the tube. The result is that although the connection or union between the fin and tube is frictional, it is so strong that there will be no shifting of the fins upon the tube under conditions of actual use, and furthermore such union provides for very efficient heat transmission.

The binding action of the fin upon the tube may be increased by passing a mandrel through the tube and thereby causing it to expand.

In order that the invention may be more fully understood reference is hereby made to the accompanying drawing of which Fig. l is a side View of a tube upon which a number of fins are mounted in accordance with my invention.

Fig. 2 is a vertical section showing a tube and fin before the latter is mounted on the former.

Fig. 3 is a similar View showing the fin'85 mounted upon the tube Without expansion of the latter.

Fig. 4 is a view similar to Fig. 3 after the tube has been expanded by a mandrel.

Figs. 5, 6 and 7 are vertical sections of 4modified forms of fins mounted upon a tube.

The tube 1 may be of any suitable material, for example copper or iron. The lin 2 may be stamped or drawn from a sheet of resilient metal or alloy into the form shown in Fig. 2. It will be noted that the diameter of the aperture 3 formed therein is substantially smaller than the exterior diameter of the tube l. The material surrounding the aperture 3 forms a flange 4, preferably united to the body 2 by a curved or bowe spring portion 5.

ln order to mount the fins upon the tube, the former may be placed in a. jig havlng grooves for Vreceiving each of the fins and holding same in spaced relation wh1le .the tube l is moved in a longitudinal direction and successively enters the apertures 3 of said fins, or thetube may be held While the fins are moved to force them upon the tube. By reason of the flexure of the bow portion 5, the flange 4 assumes the position shown in Fig. 3 in which it is Aarallel to the surface of the tube and exten s along the same in close contact therewith for a substantial distance Such contact provides for very efficient heat transmission, and furthermore by reason of the resilience of the fin material, the pressure between the flange 4 and tube 1 is considerable and the fin is very firmly held by friction against displacement. Such union may` 1f desired be further strengthened by causmg the expansion of the tubeV by passing a mandrel 6 therethrough, as shown in Fig. 4.

It is obvious that the material in proximity to the aperture 3 may take a great varietgof forms some of which are illustrated. or example, Fig. 5 shows a flange 4 united to the body of fin 2 by a reversely curved portion 7.

In Fig. 6 a flange 8 is united to body 2 by portion 5 and in Fig. 7 a flange 9 is directly united to the body 2.

Among the advantages of my invention are the followingl (1) The fins may be held on the tube with sulllcient firmness without expanding the latter, so that fins and tubes of any desired material and thickness may be employed.

(2) The area of contact between fin and tube may be increased, whereby flow of heat is facilitated and efficiency increased.

(3) In case the tube should be expanded no warping or buckling of fins will occur, and thinner metal may, therefore, be used in the making of the fin.

(4) The area of contact of fin and tube does not depend on the thickness of the fin material so that thinner fin material may be used without loss of efficiency.

(5) The extent to which the tube may be expanded without causing any buckling of the fili is increased by reason of the stretching of the flange and flexure of that portion of the fin between the flange and body portion.

(6) The fin is stifl'ened by the flange and curved or grooved portion between flange and body.

The openings or perforations 3 need not be circular, but may be oval or other desired shape. Each fin may be formed with a p1urality of perforations and a tube passed through each. Such perforations may be situated in any desired position within the fin.

The fins may be of any desired size o1' shape, and the units formed by mounting same on tubes may be assembled side by side or in banks one above another. The cross section of the tubes may be circular, oval or other desired shape.

My invention is not limited to the use of fins having perforations 3 of smaller diameter than the external diameter of the tube 1. The fin may be of the form shown in Fig. 3 before being placed on the tube and the latter then expanded by use of a mandrel 6 sufliciently to cause the fin to be firmly united to the tube by frictional engagement therewith.

The degree of resiliency of the fin materials may vary widely and various materials may be used, as for example, but without limitation thereto, copper, aluminum, steel, nickel, and various alloys of such metals, for example monel metal. Any metal or alloy having sufficient ductility and resiliency for forming the Hange 4 and curved portion 5 may be used.

Having now described my invention, what I claim is:

l. A heat exchange apparatus comprising a tubular support and a fln mounted thereon, said fin consisting of a perforated sheet of relatively elastic sheet metal having an integral flange surrounding the perforation, said flange being expanded upon said support to grip the same by its contraction and contacting with said tubular support for a substantial distance along the length thereof and being united to the body of the fin by a relatively yieldable bowed portion which is flexed within its elastic limit.

2. The method of making tubes having llns which consists in taking a relatively elastic sheet, forming therein a flanged aperture and a bowed portion intermediate the flange and the outer portion of the sheet adapted to yield to provide spring resistance, and inserting a tube through said flange and expanding the latter against the yieldable resistance of said bowed portion by the action of the tube to cause said flange to grip said tube over an extended surface without distort-ing the outer portion of the fin.

3. The method of making tubes having fins which consists in taking a metallic sheet, forming therein a flanged aperture and a bowed spring portion intermediate the flange and the outer portion of the sheet, and inserting a tube of greater diameter than that of said flange through said flange to expand the latter against the yieldable resistance of said spring portion and cause said flange to frictionally grip said tube bythe combined effect of the contracting action of the flange and the spring portion, distortion of the portion of the fin beyond the spring portion being prevented by transmitting the stresses due` to the flange expansion to said s ring portion.

4. The method of making tu es having fins which consists in taking a relatively elastic metallic sheet, forming therein a flanged aperture and a bowed portion intermediate the flange and the outer portion of the sheet of relativel greater yieldability than the flange and t e outer portion of the fin, inserting a relatively rigid tubeof greater diameter than that of said flange through said flange to expand the latter against the yieldable resistance of said bowed portion and cause said flange to frictionally grip said tube by the combined effect of the contracting action of the flange and the bowed portion, distortion of the portion of the fin beyond the bowed 15 portion being prevented by transmitting the stresses due to the flangeexpansion to said bowed portion, and. expanding the tube, by distortion thereof to increase the gripping action. l v 5. In apparatus of the character described, a fin of relatively elastic metal having a flanged aperture and a bowed portion of relative y greater yieldability formed therein at the juncture of the flange with the body of the fin, and a relatively rigid tube received within said flange and expanding the latter against the spring resistance of said bowed portion, said flange under the contracting action due to the inherent elasticitythereof and under the spring action of said bowed i portion frictionally gripping said tube, and said bowed portion receiving the stresses due to the expansion of the fil-ange for preventing the distortion of the body portion bf the flIl. l

In testimony whereof, I have signed my name hereto. l'

PARKER o. .KALLooiL JR.. 

